The manufacture of liquid crystal displays, flat panel displays, thin film transistors and other semiconductor devices occurs within a plurality of chambers, each of which is designed to perform a specific process on the substrate. Many of these processes can result in an accumulation of material (e.g., material deposited on the substrate in layers, such as by chemical vapor deposition, physical vapor deposition, thermal evaporation, material etched from substrate surfaces, and the like) on chamber surfaces. Such accumulated material can crumble from the chamber surfaces and contaminate the sensitive devices being processed therein. Accordingly, process chambers must be cleaned of accumulated materials frequently (e.g., every 1-6 substrates).
To clean chamber surfaces, an in-situ dry cleaning process is preferred. In an in-situ dry cleaning process one or more gases are dissociated within the processing chamber to form one or more reactive gas species (e.g., fluorine ions, radicals). The reactive species clean chamber surfaces by forming volatile compounds with the material accumulated on those surfaces. Such an in-situ cleaning process reduces both particle counts and the system down time required for more interruptive cleaning processes which require the chamber to be opened.
Remote Plasma Source Cleaning (RPSC) is a further improvement to the in-situ plasma clean. In a RPSC, cleaning gas(es) are dissociated in a separate chamber, and the dissociated reactive species are then flowed downstream into the processing chamber where they clean/etch material from chamber surfaces. RPSC fully dissociates the cleaning gas and thus provides significant savings both monetarily and environmentally. In addition, RPSC reduces chamber consumables by eliminating the detrimental ion-bombardment associated with in-situ plasma cleaning processes.
Unfortunately, as described further below, both insitu cleaning and remote plasma source cleaning processes conventionally require considerable time and consume considerable amounts of cleaning gases, and thus undesirably increase the cost per substrate processed within a processing chamber. Further, in Remote Plasma Source Cleaning (RPSC) large cleaning rate variations often are observed between processing chambers cleaned by identical cleaning processes. Accordingly, there is a need for an improved method and apparatus for etching accumulated material from chamber surfaces.